MICROPROCESSOR IN MECHATRONICS

ARCHITECTURE OF 8085 MICROPROCESSOR:

Accumulator:-

It is a 8-bit register which is used to perform airthmetical and logical operation. It stores the output of any operation. It also works as registers for i/o accesses.

Temporary Register:-

It is a 8-bit register which is used to hold the data on which the acumulator is computing operation. It is also called as operand register because it provides operands to ALU.
Registers:-

These are general purposes registers. Microprocessor consists 6 general purpose registers of 8-bit each named as B,C,D,E,H and L.   Generally theses registers are not used for storing the data permanently. It carries the 8-bits data. These are used only during the execution of the instructions.

These registers can also be used to carry the 16 bits data by making the pair of 2 registers. The valid register pairs available are BC,DE HL. We can not use other pairs except BC,DE and HL. These registers are programmed by user.

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ALU:-

  ALU performs the airthmetic operations and logical operation.

Flag Registers:-

It consists of 5 flip flop which changes its status according to the result stored in an accumulator. It is also known as status registers. It is connected to the ALU.

There are five flip-flops in the flag register are as follows:
1.Sign(S)
2.zero(z)
                               3.Auxiliary carry(AC)
     4.Parity(P)
    5.Carry(C)
The bit position of the flip flop in flag register is:

All of the three flip flop set and reset according to the stored result in the accumulator.

1.Sign-

 If D7 of the result is 1 then sign flag is set otherwise reset. As we know that a number on the D7 always desides the sign of the number.

if D7 is 1: the number is negative.
if D7 is 0: the number is positive.

2.Zeros(Z)-

If the result stored in an accumulator is zero then this flip flop is set otherwise it is reset.

3.Auxiliary carry(AC)-

If any carry goes from D3 to D4 in the output then it is set otherwise it is reset.

4.Parity(P)-

If the no of 1's is even in the output stored in the accumulator then it is set otherwise it is reset for the odd.

5.Carry(C)-

If the result stored in an accumulator generates a carry in its final output then it is set     otherwise it is reset.

Instruction registers(IR):-It is a 8-bit register. When an instruction is fetched from memory then it     is stored in this register.

Instruction Decoder:- Instruction decoder identifies the instructions. It takes the informations from instruction register and decodes the instruction to be performed.

Program Counter:-

It is a 16 bit register used as memory pointer. It stores the memory address of the next instruction to be executed. So we can say that this register is used to sequencing the program. Generally the memory have 16 bit addresses so that it has 16 bit memory.The program counter is set to 0000H.

Stack Pointer:-

It is also a 16 bit register used as memory pointer. It points to the memory location called stack. Generally stack is a reserved portion of memory where information can be stores or taken back together.

Timing and Control Unit:-

It provides timing and control signal to the microprocessor to perform the various operation.It has three control signal. It controls all external and internal circuits. It operates with reference to clock signal.It synchronizes all the data transfers.

There are three control signal:

1.ALE-Airthmetic Latch Enable, It provides control signal to synchronize the components of            microprocessor.

2.RD- This is active low used for reading operation.

3.WR-This is active low used for writing operation.

There are three status signal used in microprocessor S0, S1 and IO/M. It changes its status

     according the provided input to these pins.

Serial Input Output Control-

There are two pins in this unit. This unit is used for serial data communication.

Interrupt Unit-

There are 6 interrupt pins in this unit. Generally an external hardware is connected to these pins. These pins provide interrupt signal sent by external hardware to microprocessor and microprocessor sends acknowledgement for receiving the interrupt signal.Generally INTA is used for acknowledgement. 

PIN DIAGRAM OF 8085 MICROPROCESSOR :

8085 is a general purpose microprocessor having 40 pins and works on single power supply. To study the pin diagram we group
 the signals into 5 categories:

1.Power Supply
2.Clock Signals
3.Interrupt Signals
4.Address and Data bus
5.Control and Status signals
6.Serial I/O Port
7.DMA Request Signals

Power Supply Signal and clock signal:

VCC:-

Vcc is to be connected to +5V power supply.

Vss:-

Ground reference

X1 and X2:- 

This pin is used for providing the clock frequency to the microprocessor. Generally Crystal oscillator or LC oscillator is used to generate the frequency. The frequency generated here is internally divided into two.As we know that the basic operating timing frequency of the microprocessor is 3 MHz so 
6 MHz frquency is applied.

Serial Input Output port:-

SID and SOD:-

These pins are used for serial data communication.

Interrupt Signal:-

Pin 6 to 11:- 

These pins are used for interrupt signals. Generally and external devices are connected here which requests the microprocessor to perform a particular task.
There are 5 pins for hardware interrupts-
TRAP, RST7.5, RST 6.5, RST5.5 and INTR
INTA is used for acknowledgement. Microprocessor sends the acknowledgement to external devices through the INTA pin.
Address Bus and DATA Buses:-

AD0-AD7:-

These are multiplexed address and data bus. So it can be used to carry the lower order 8 bit address as well as the data. Generally these lines are demultiplexed using the Latch.
During the opcode fetch operation, in the first clock cycle the lines deliever the lower order address bus  A0-A7.
In the subsequent IO/M read or write it is used as data bus D0-D7. CPU can read or write data through these lines.

A8-A15:-

These are address bus used to address the memory location.

Control And Status Signal:-

S0 and S1:-

It is used for the status signal in microprocessor.

ALE(Airthmetic Latch Enable):-

This signal is used to capture the lower address presented on multiplexed address and data bus.

RD:-

This is active low input generally used for reading operation.

WR:-

This is active low input used for writing operation.

IO/M:-

This pin is used to select the memory or input-output through which we want to communicate the data.
READY:-

As we know that memory and input -output have slower response than microprocessor. So a microprocessor may now be able to handle further data till it completes the present job. So it is in waiting state. As it completes the present job it sets the READY pin. Microprocessor enters into wait state while READY pin is disabled.

RESET IN:-

This is active low input. This pin is used to reset the microprocessor. An active low signal applied to this pin reset the program counter inside the microprocessor. The busses are tristated.

RESETOUT:-

If we want to reset the external devices connected to the microprocessor then a signal applied to this pin resets the external devices.
DMA Request Signal:

HOLD and HLDA:-

HOLD is an active high input signal used by the other controller to request microprocessor about use of address, data and control signal. The HOLD and HLDA signal are used for direct memory access(DMA). DMA controller receives a requests from a device and in turn issues the HOLD signal to the microprocessor.
The processor releases the system bus and then acknowledges the HOLD signal with HLDA signal. The DMA transfer thus begins.

ADC  DAC CONVERTERS:

Data Conversion Devices are very important components of a Machine Control Unit (MCU). MCUs are controlled by various computers or microcontrollers which are accepting signals only in Digital Form i.e. in the form of 0s and 1s, while the signals received from signal conditioning module or sensors are generally in analog form (continuous). Therefore a system is essentially required to convert analog signals into digital form. Analog to Digital Converter is abbreviated as ADC. Figure shows a typical control system with data conversion devices.

Based on the signals received from sensors, MCU generates actuating signals in the Digital form. Most of the actuators e.g. DC servo motors only accept analogue signals. Therefore the digital signals must be converted into Analog form so that the required actuator can be operated accordingly. For this purpose Digital to Analog Converters are used, which are abbreviated as DACs. 

A control system with ADC and DAC devices

Basic components used in ADCs and DACs:

1. Comparators:

In general ADCs and DACs comprise of Comparators. Comparator is a combination of diodes and Operational Amplifiers. A comparator is a device which compares the voltage input or current input at its two terminals and gives output in form of digital signal i.e. in form of 0s and 1s indicating which voltage is higher. If V+ and V- be input voltages at two terminals of comparator then output of comparator will be as

V + > V - → Output 1

V + < V - → Output 0

2. Encoders:

Though the output obtained from comparators are in the form of 0s and 1s, but can't be called as binary output. A sequence of 0s and 1s will be converted into binary form by using a circuit called Encoder. A simple encoder converts 2ⁿ input lines into ‘n' output lines. These ‘n' output lines follow binary algebra.

3. Analog to Digital Converter (ADC):

As discussed in previous section ADCs are used to convert analog signals into Digital Signals. There are various techniques of converting Analog Signals into Digital signals which are enlisted as follows. 

1.Direct Conversion ADC:

Circuit of  ADC

Above Figure shows the circuit of Direct conversion. To convert a digital signal of N-bits, ADC requires 2^N -1 comparators and 2^N resistors. The circuit provides the reference voltage to all the comparators. Each comparator gives an output of 1 when its analog voltage is higher than reference voltage or otherwise the output is 0. In the above circuit, reference voltages to comparators are provided by means of resistor ladder logic.

The circuit described in figure  acts as 3 Bit ADC device. Let us assume this ADC works between the range of 0-10 Volts. The circuit requires 7 comparators and 8 resisters.Now the voltages across each resistor are divided in such a way that a ladder of 1 volt is built with the help of 1K-Ohm resistances. Therefore the reference voltages across all the comparators are 1-7 volts.

Now let us assume that an input voltage signal of 2.5 V is to be converted into its related digital form. As 2.5V is greater than 1V and 2V, first two comparators will give output as 1,1. But 2.5V is less than 3,4,5,6,7 V values therefore all other comparators will give 0s. Thus we will have output from comparators as 0000011(from top). This will be fed to the encoder logic circuit. This circuit will first change the output in single high line format and then converts it into 3 output lines format by using binary algebra. Then this digital output from ADC may be used for manipulation or actuation by the microcontrollers or computers.

Digital to Analog Converters:

1 Binary Weighted DAC:

Circuit of binary weighted DAC

An op-amp used in DAC

As name indicates, in binary weighted DAC, output voltage can be calculated by expression which works on binary weights. Its circuit can be realized in Figure . From the figure it can be noted that most significant bit of digital input is connected to minimum resistance and vice versa. Digital bits can be connected to resistance through a switch which connects resistance-end to the ground . The digital input is zero when former bit is connected to reference voltage and if it is 1. This can be understood from Figure . DAC output voltage can be calculated from property of operational amplifiers. If V1 be input voltage at MSB (most significant bit), V2 be input voltage at next bit and so on then for four bit DAC we can write,

   

Here V₁, V₂, V₃, V₄, will be Vref if digital input is 1 or otherwise it will be zero.

Hence output voltage can be found as:

However Binary weighted DAC doesn't work for multiple or higher bit systems as the value of resistance doubles in each case.

Thus simple and low bit digital signals from a transducer can be converted into a related continuous value of voltages (analogue) by using binary weighted DAC. These will further be used for manipulation or actuation.

2.R-2R Ladder based DAC:

R-2R Ladder based DAC

n R-2R ladder logic, shortcoming of Binary Logic has been removed by making the value of maximum resistance double however the rest of the circuit remains same.Figure 2.8.5 shows the circuit of R-2R Ladder based DAC. If we apply voltage division rule in above case, then we can calculate that output voltage as,

Where V_AL can be calculated from the digital signal input as,

In this way output voltage is obtained by converting the digital signals received from microprocessor/ microcontroller. These voltages will further be used to actuate the desired actuator viz. DC/AC motors. In this module we have studied the principle of operation of various sensors which are commonly used in mechatronics and manufacturing automation. Also the signal conditioning operations and the devices which are used to generate the proper signals for desired automation application have been studied. In the next module we will study the construction and working of microprocessor and the devices which are being used in controlling the various operations of automation using the microprocessors.

ELECTRICAL DRIVES,SENSORS ,PLC ,MECHATRONICS SYSTEMS,SPEED SHAFT CONTROL

for the 3rd unit go through this pdf
https://drive.google.com/open?id=0ByqadBQSN1SnVHFiTlZ1QTByRXc&authuser=0

SENSORS ,PLC ,MECHATRONICS SYSTEMS
https://drive.google.com/open?id=0ByqadBQSN1Sndll6S2xHSUlVamc&authuser=0

https://drive.google.com/open?id=0ByqadBQSN1SnOTkyVGdud3FuZHc&authuser=0

SHAFT SPEED CONTROL SYSTEM:

Fig shows a simple automatic control system for the speed of  rotation of a shaft.A potentiometer is used to set the reference value. i.e what voltage is supplied to the differential amplifier as the reference value for the required  speed of rotation. The differential amplifier is used to both compare and amplify the difference between the reference and feedback values, i.e it amplifies the error signal. The amplified error signal is then fed to a motor which in turn adjusts the speed of the rotating shaft.

The speed of the rotating shaft is measured by the tachogenerator , connected to the rotating shaft by means of pair of bevel gears. The signal from the tachogenerator is then fed back to the differential amplifier.

controlled valve -sped of rotation of shaft 

reference value-setting of slider on potentiometer 

comparison element-differential amplifier

error signal-the difference between the output from the potentiometer and that from the tachogenerator system

control unit-the differential amplifier

correction unit-the motor

process-the rotating shaft

measuring device- the tachogenerator

ENGINE MANAGEMENT SYSTEM

ENGINE MANAGEMENT SYSTEM

Engine management system is, now-a-days, used in many of the modern cars such as Benz, Mitsuibisi, and Toyota etc.This system uses many electronic control system involving micro controllers.The generalized block diagram of this system is shown in fig

The objective of the system being to ensure that the engine is operated at its optimum settings.

The system consists of many sensors for observing vehicle speed, engine temperature, oil and fuel pressure, airflow etc. These sensors are supplying input signals to the micro controller after suitable signal conditioning and providing output signals via drivers to actuate corresponding actuators. 

A single cylinder engine consists of some of these elements in relation to an engine is shown in fig.The engine sensor is an inductive type s It consists of a coil and sensor wheel.The inductance of the coil changes as the teeth of the sensor wheel pass it and so results in an oscillating voltage.

 

The engine temperature sensor is generally thermocouple which is made of bimetallic strip or a thermistor.The resistance of the thermistor changes with change in engine temperature this results in voltage variation.Hot wire anemometer is used as a sensor for measuring mass airflow rate.The basic principle is that the heated wire will be cooled as air passes over it.The amount of cooling is depending on the mass rate of flow.

The oil and pressure sensors are diaphragm type sensors. According to the pressure variation, the diaphragm may contract or expand and activates strain gauges which produces voltage variation in the circuit.

The oxygen sensor is usually a close end tube which is made of ZirConium oxide with porous platinum electrode on the inner and outer Surfaces.The sensor becomes permeable to oxygen ions at about 300°C.This results in generation of voltage between the electrodes.The various drivers such as fuel injector drivers, ignition coil drivers. solenoid drivers are used to actuate actuation according to the signal by various sensors.

Analog signals given by sensors are converted into digital signal by using analog to digital converters (ADC) and sent it to micro controllers.The various output digital signals are converted into analog signals by DAC(i.e., Digital to Analog Converter) and shown in various recorders or meters.

CAR PARK BARRIERS,COIN COUNTERS,BAR CODE READER

The system uses a PLC for its operation.There are two barriers used namely in barrier and out barrier. In barrier is used to open when the correct money is inserted while out barrier open when the car is detected in front of it.It shows a schematic arrangement of an automatic car park barrier. It consists of a barrier which is pivoted at one end, two Solenoid valves A and B  and a piston cylinder arrangement.

A connecting rod connects piston and barrier as shown in fig below Solenoid valves are used to control the movement of the piston.Solenoid A is used to move the piston upward inturn barrier whereas solenoid B is used to move the piston downward.

 

Limit switches are used to detect the foremost position  of the barrier. When current flows through solenoid A, the piston in the cylinder moves upward and causes the barrier to rotate about its pivot and raises to let a car through it.

COIN COUNTERS:

Coin counters which accepts mixed denomination of coins.The system should identify the denomination of coins through sensors.The sensor output is to be interfaced to electronic circuitry that should indicate no of coins presented and total value of coins.These two values must be displayed in multiplexed display.

The design is divided into two parts:

 1.Mechanical design

 2.Electronic design

MECHANICAL DESIGN:

It requires a chamber to accept mixed denomination of coins and mechanism to present the coins to sensor array which can read their attributes and output digital signals for computations.A typical horizontal slotted design is shown in fig.Dc motor is used to rotate the disk,as the disk rotate the coin drops into the slot which contains array of sensors.As the size ,weight and thickness of every coin is unique for different coins.This feature of coin is used to determine the value of coins by well designed sensing system.

ELECTRONIC DESIGN:

For determining combination of each different denominations a set of phototransistor - photodiode pairs are used.The signal from these sensors are pulses of different widths with different starting times depending on size and speed of coin.

The sensor output is converted to TTL(Transistor–transistor logic) signals by using schmitt triggers , so the outputs can be compatible to the electronic circuitry.A sequential logic circuit is designed to identify the coin correctly.The Boolean expression   for the different denomination of coins is to be developed.

  e.g

          X= A̅ B̅ C̅

Where 

        A,B,C-corresponds to the sensor output

BAR CODE READER:

The familiar scene at the checkout of a supermarket is of the purchase being passed in front of a light beam or a hand-held wand being passed over the goods so that the bar code can be read and the nature of the purchase and hence its price automatically determined. The code consists of a series of black and white bars of varying widths. For example there is such a bar code on the back of this book. 

Fig shows the basic form of the bar code used in the retail trade. The bar code represents a series of numbers.There is a prefix which identifies the coding scheme being used.This is a single digit for the regular universal product coding scheme used in the US and two digits for the european article number scheme used in europe. The upc uses a 0 prefix for grocery and a 3 for pharmaceuticals. The EAN prefix is from 00 to 09 and is such the UPC code ca be read within the EAN code. This is followed by five digits to represent the manufacturer each manufacturer having been assigned a unique number.This brings up the center of the code pattern which is identified by two taller bar patterns. The five digit number that then follows represents the product.The final number is a check digit which is used to check that the code has been correctly read. A guard pattern of two taller bars at the start and end of the bar pattern is used to frame the bars.

Each number is coded as seven 0 or 1 digits .The codes used on either side of the centre line are different so that the direction of the scan can be determined. To the right the characters have an even number  of 1s and so even parity and for  UPC to the left an odd number of 1s and so odd parity.The EAN coding for the left being a mixture.

Table shows the UPC being the left A coding and the EAN using both left A and left B character codes.

EX: 1101100

Each 1 is entered asa dark bar and thus the right hand character 2 would be represented 1101100 and with the adjacent dark bars run together ,it appears as a double width space. The guard pattern at the ends of the code represents 101 and the central band of bars is 01010.

The bar code shown in the the fig is using the EAN code and has the prefix 97 to identify it as a publication , 80582 to identify the publisher ,25634 to identify the particular book and a check digit of 7. note that the bar code contains the relevant parts of the ISBN number ,this also being a number to identify the publisher and the book concerned .

PICK AND PLACE ROBOTS

PICK AND PLACE ROBOTS

• Pick and place robot speeds up the process of picking parts up and placing them in new locations, while also increasing production rates.The consistency, quality and repeatability  of a pick and place robot system is unmatched.These systems are also versatile and can be reprogrammed and tooled to provide multiple applications for consumers.

• An increase in output with a pick and place robot system offer long-term savings to companies with the advancements in technology and affordability of robots, more pick and place robots are being installed for automation applications.

    The basic form of pick and place robot is shown in Fig.

• The robot has three axis about which motion can occur.The following movements are required for the robot.

1. clockwise,anticlockwise,rotation of robot unit on its own axis.
2. Linear movement of arm horizontally. i.e extension or contraction of the arm.
3. Up and down movement of the arm.
4. open and close movement of the gripper.

• The foresaid movements can be obtained by pneumatic cylinder which is operated by solenoid valves with limit switches.Limit switches are used to indicate when a motion is completed. 

• The clockwise rotation of the robot unit on its base can be obtained from a piston and cylinder arrangement during pistons forward movement. Similarly counter clockwise rotation can be obtained during backward movement of the piston in cylinder.

APPLICATIONS:

1. It can be used in Production industry.

2. In mass production.

3. In Automobile Industry.

4.High speed assembly.

5.Packing

ADVANTAGES:

               Quality: 

                Industrial automated mechanical arm have the capacity to dramatically improve product                 quality. Applications are performed with precision and high repeatability every time. This                 level of consistency can be hard to achieve any other way.

               Production:
         With mechanical arm, throughput speeds increase, which directly impacts production.                  Because an automated mechanical arm has the ability to work at a constant speed                      without pausing for breaks, sleep, vacations, it has the potential to produce more than a                human worker.

              Safety:
         mechanical arm increase workplace safety. Workers are moved to supervisory roles                      where they no longer have to perform dangerous applications in hazardous settings.

              Savings: 
         Improved worker safety leads to financial savings.Automated mechanical arm also offer                  untiring performance which saves valuable time. Their movements are always exact,                       minimizing material waste.

DIS-ADVANTAGES:

Expense:
Regular maintenance needs can have a financial toll as well.

ROI: 
Incorporating industrial robots does not guarantee results. Without planning, companies can have difficulty achieving their goals.

Expertise:
Employees will require training program and interact with the new robotic equipment. This normally takes time and financial output.

Safety:
Robots may protect workers from some hazards, but in the meantime, their very presence can create other safety problems. These new dangers must be taken into consideration.

WINDSCREEN WIPER WING STEPPER MOTOR CONTROL

 Windscreen wiper wing stepper motor control:

·        Windscreen wiper is a device which is used to clear the front glass of the cars,buses, train etc., during raining days. It will oscillate an arm back and forth in an arc like a windscreen wiper. A traditional mechanical solution for this problem is shown in fig.

·    It uses a brush-less stepper motor.It uses a principle of four-bar mechanisms.It is using a worm and gear to reduce the speed and to increase the torque up to 50:1. It consists of a crank which rotates about its center and a connecting rod which converts rotary movement to linear movement of the linkage .  An end of a connecting rod is connected to the crank and other with wiper arm. Rotation of crank causes connecting rod to impart an oscillatory motion to wiper arm. We can also have wiper arm in the passenger side, a linkage will connect both the sides.

·     An alternative mechatronics approach for this problem is to use a stepper motor. For operating a stepper motor a microprocessor or a micro controller can be used.The input to the stepper motor is required to cause it to rotate a number of steps in one direction and reversing the same number of steps in other direction while the data is reversed.

  

.

Rain Sensor:

·         When the vehicle is started the rain sensor gets the supply power and it will scan for the moisture content in the windshield.The sensor is interfaced with the micro controller. An infrared beam is reflected off the outside surface of the windshield to the infrared sensor array. When moisture strikes the windshield, the system experiences an interruption to its infrared beam. Advanced analog and  digital signal processing determines the intensity of rain or snow. The sensor communicates to the wiper control module to switch on the wiper motor and controls the wipers automatically according to the moisture intensity detected.

• The sensor will send output voltage according to the rain amount. If there is no rain then the voltage will be more than 4V and if it is raining the output will be less than 4V. When rain is detected then the motor will be turned on at lower speed. If the voltage drops less than 2.5V then the motor will be turned ON at higher speed.

TYPES:

 .

b